A conventional power device for a pneumatic packing tool has a pneumatic motor. The pneumatic motor has an air inlet, an impeller, and an air outlet. When a high-pressure gas is inputted into the air inlet of the pneumatic packing tool, the impeller is brought to rotate and generate a mechanical force for tightening a packing belt so that an article can be packed quickly.
However, during the process of packing, since the pneumatic packing tool is inputted with a high-pressure gas, when the high-pressure gas is exhausted via the air outlet, a large amount of noise will be generated, which will affect the hearing of the user after a long period of time. Therefore, the air outlet is blocked with a fabric, a net or other material to achieve the purpose of noise reduction. But, this way reduces the output efficiency of the pneumatic packing tool. Moreover, the conventional pneumatic packing tool uses a turning valve to change the direction of the rotation of the pneumatic packing tool, which increases the complexity of production and operation. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.